Short term for GNU/Linux. This operating system is created to be stable, fast, and secure. It comes in different flavors "distros" to suit everybody's needs. Help is available everywhere except from the Windows idiot. Linux is a made as open-source to allow people to edit linux itself to suit their own needs. Linux will only crash if you are too attach to windows to let go of it.
Windows in the other hand is EXPENSIVE! Windows comes with little good software, and extra applications will cost you big time. That nice noise they have when you boot is important, cause you'll have to hear that alot in one day.
Has different window managers and different desktops for different people to use. You could even make you're own window manager or desktop.
When I installed Mandrake Linux. It was easy and simple to use. I had it barely configured and used it only to help me on my homework. Then I got Nvidia drivers for my video card, and started gaming and other stuff. Now, Linux is the only thing I ever need.
Windows is a piece of crap and some nice alternatives are BSD, Mac OS X, and Solaris. These are UNIX based and are some of the best operating systems.
I can play Unreal Tournament with 1024x768 highest quality with a stable 15 fps on my Intel Celeron 500mhz, 196 mbs of ram, geforce 2 420 computer while on Linux. Windows, I can only run it with 640x480, lowest quality, with only about 8 fps.
Linux is the perfect machine for games! Nintendo and Sony, make a new console with Linux and you'll school any X-Box 2!